It is common practice in blow molding of plastic articles to continuously extrude a parison at one work station and to blow mold the parison to form the article at another work station. In such an arrangement, a pair of mold sections are actuated between open and closed positions by a clamp which is movable between the work stations. It is known to mount the clamp on a table which is adapted for limited vertical movement at the work stations or during movement therebetween. Severing means are provided at the extruding station for severing the parison from the extruder. In this arrangement, the mold sections are closed by the clamp at the extruding station; the parison is severed and the table is dropped a short distance to prevent the parison from resticking. The clamp is moved relative to the table to the blow station where a blow pin enters the parison to admit compressed air to expand the parison in the mold sections to form the article. During this operation, the table is raised to its initial level. After the article is formed, the mold sections are opened by the clamp and the clamp is returned to the extruding station and the cycle is repeated. It is also known to mount a pair of trimming members to move with the mold sections so as to remove the flash from the formed article at the blow station when the mold sections are moved to the closed position at the extruding station. A blow molding machine of this type described is disclosed in my U.S. Pat. No. 4,248,582.
A problem in the prior art is that of providing a clamp which is capable of exerting the large closing force required on the mold sections and which affords the desired clearance for movement between the work stations.
Further, there is need for an improved lifting mechanism capable of supporting the clamp and imparting vertical movement thereto with a quick dropping motion.
Another problem in the prior art has been that of trimming the flash from the formed article with simple and reliable trimming equipment.
A general object of this invention is to provide a blow molding machine with particular improvements over the prior art.